Fixed a typo that we don't export all symbols.

ConfigureChecks.cmake

@@ -16,9 +16,9 @@ set(SYSCONFDIR ${SYSCONF_INSTALL_DIR})
 set(BINARYDIR ${CMAKE_BINARY_DIR})
 set(SOURCEDIR ${CMAKE_SOURCE_DIR})
 
-if(CMAKE_COMPILER_IS_GNUC)
+if(CMAKE_COMPILER_IS_GNUCC)
 check_c_compiler_flag("-fvisibility=hidden" WITH_VISIBILITY_HIDDEN)
-endif(CMAKE_COMPILER_IS_GNUC)
+endif(CMAKE_COMPILER_IS_GNUCC)
 
 # HEADER FILES
 check_include_file(argp.h HAVE_ARGP_H)